Glass plate, laminate, and display device

Abstract

The purpose of the present invention is to provide glass capable of improving the light extraction efficiency. The glass plate has a first main surface and a second main surface facing the first main surface, has a thickness of 0.30-1.00 mm, and satisfies formulas (1) and (2) with expression as the mass percentage on an oxide basis.　(1): 0.03 ≤ (ΔSnO2)T ≤ 1.0; (2): 0.20 ≤ (ΔSnO2)B ≤ 1.5

Description

Glass plate, laminate and display device

[0001] The present invention relates to a glass plate, a laminate, and a display device.

[0002] Chemically strengthened glass is glass in which an ion exchange occurs between alkali ions contained in the glass and alkali ions with a larger ionic radius contained in the molten salt composition, for example by immersing the glass in a molten salt composition such as sodium nitrate, thereby forming a compressive stress layer in the surface layer portion of the glass.

[0003] Chemically strengthened glass is widely used in applications requiring strength, such as protective materials for display devices such as mobile phones, smartphones, and tablet terminals, building materials such as window glass, tabletops, and interiors of automobiles and airplanes, as well as protective materials therefor (see, for example, Patent Document 1).

[0004] In chemically strengthened glass, the refractive index of light increases in the chemically strengthened region. In chemically strengthened glass in which the surface layer of the glass is ion-exchanged, the refractive index of light in the surface layer increases and tends to approach the refractive index of light at the center of the plate thickness from the surface layer to the interior (Patent Document 2).

[0005] International Publication No. 2019 / 070005 Japanese Patent Application Laid-Open No. 2012-211051

[0006] When chemically strengthened glass with an ion-exchanged surface layer is used as a protective member for a component having a light-emitting element, such as a display device, there is a problem in that the light extraction efficiency from the light-emitting element decreases.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a glass plate that can improve light extraction efficiency.

[0008] The inventors have added SnO ２ The inventors have found that the light extraction efficiency can be improved by providing a concentration distribution, and have completed the present invention.

[0009] That is, the present invention is as follows: 1. A glass plate having a first main surface and a second main surface opposite to the first main surface, a thickness of 0.30 to 1.00 mm, and satisfying the following formulas (1) and (2) in terms of mass percentage based on oxides: 0.03≦(ΔSnO ２ ) Ｔ ≦1.0 (1) 0.20≦(ΔSnO ２ ) Ｂ ≦1.5 (2) (ΔSnO ２ ) Ｔ : [SnO at the center of the plate thickness ２ concentration (%)] to [SnO ２ Concentration (%)] minus the value (%) (ΔSnO ２ ) Ｂ : [SnO on the second main surface ２ concentration (%)] to [SnO at the center of the plate thickness ２ 2. The mass percentage of SnO at a depth of 100 μm from the first main surface, expressed as an oxide-based mass percentage. ２ From the concentration (%), SnO ２ 3. The glass plate according to 1 above, wherein the value obtained by subtracting the concentration (%) of SnO on the second main surface is 0 to 0.9%, expressed as a mass percentage based on oxides. ２ From the concentration (%), SnO at a depth of 100 μm from the second main surface ２ 3. The glass plate according to 1 or 2 above, wherein the value obtained by subtracting the concentration (%) of SiO from the base composition is 0.15 to 1.4%, expressed as a mass percentage based on oxides: ２ 55 to 75% Al ２ O ３ 7.0-30%, Li ２ 5. The glass plate according to any one of 1 to 3 above, containing 0.01 to 13.0% of O. 5. The base composition, expressed as a mass percentage based on oxides, is: SiO ２ 55 to 75% Al ２ O ３ 7.0-30%, Li ２ O 0.01-13.0%, Na ２ O 0 to 18%, ZrO ２ 0.1 to 6.0%, Y ２ O３ 1.0 to 9.0%, P ２ O ５ 6. The glass plate according to any one of 1 to 4 above, containing 0 to 5.0% of the following: SiO ２ 60 to 66% Al ２ O ３ 23-27%, Li ２ 3.5-5.0% O, Na ２ O 1.0 to 2.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5%, SnO ２ 7. The glass plate according to any one of 1 to 4 above, containing 0.4 to 1.0% of the following: ２ 60 to 66% Al ２ O ３ 18-24%, Li ２ 4.0-6.0% O, Na ２ O 0.5 to 1.5%, K ２ 0.1-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.0 to 3.5% SnO ２ 8. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of the following: SiO ２ 56 to 60%, Al ２ O ３ 25-29%, Li ２ 4.5-7.0% O, Na ２ O 0.3 to 1.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5%, SnO ２ 9. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of the following: ２ 60 to 64%, Al ２ O ３20-24%, Li ２ 3.5-5.5% O, Na ２ O 0.8 to 1.5%, K ２ 0.5-1.0% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5%, SnO ２ 10. The glass plate according to any one of 1 to 4 above, containing 1.5 to 3.0% of the following: ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 11. The glass plate according to any one of 1 to 4 above, containing 2.0 to 3.0% of the following: SiO ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.0 to 3.5% SnO ２12. The glass plate according to any one of 1 to 5 above, which is crystallized glass. 13. The glass plate according to any one of 1 to 12 above, which is chemically strengthened glass. 14. The glass plate according to any one of 1 to 13 above, which is float glass. 15. The glass plate according to any one of 1 to 14 above, which has a visible light transmittance of 91.0% or more when converted into a glass with a thickness of 0.7 mm. 16. A laminate comprising the glass plate according to any one of 1 to 15 above and a liquid crystal glass plate, wherein a lamination surface of the glass plate with the liquid crystal glass plate is the second main surface, and an absolute value of the difference between the refractive index of the second main surface of the glass plate, measured with a prism coupler, and the refractive index of the liquid crystal glass plate, measured with a prism coupler, is 0.001 to 0.20. 17. A display device comprising the glass plate according to any one of 1 to 15 above or the laminate according to 16 above.

[0010] According to the glass plate of the present invention, SnO ２ The glass plate of the present invention has a refractive index distribution resulting from the concentration distribution, which can improve the light extraction efficiency. By using the glass plate of the present invention as a protective member for a display device, the extraction efficiency of light emitted by a light-emitting element can be improved, thereby achieving power saving.

[0011] FIG. 1 is a graph showing the glass plate according to one embodiment, with the horizontal axis representing the depth from the first main surface and the vertical axis representing SnO ２ 2A and 2B are diagrams showing an aspect of the relationship between the depth from the first main surface of the glass plate according to one embodiment and the SnO concentration. ２ 3 is a diagram showing an embodiment of the relationship between the concentration and the glass melting point.

[0012] Hereinafter, the glass plate of the present invention will be described in detail based on embodiments, but the present invention is not limited to the following embodiments and can be practiced with any modifications within the scope of the gist of the present invention.

[0013] In this specification, "chemically strengthened glass" refers to glass after chemical strengthening treatment, and "glass for chemical strengthening" refers to glass before chemical strengthening treatment.

[0014] In this specification, the glass composition of chemically strengthened glass is sometimes referred to as the base composition of chemically strengthened glass. In chemically strengthened glass, a compressive stress layer due to ion exchange is usually formed on the surface of the glass, so the glass composition of the non-ion-exchanged portion is identical to the base composition of chemically strengthened glass. Furthermore, even in the ion-exchanged portion, the concentrations of components other than alkali metal oxides are essentially unchanged in terms of oxide-based mole percentage. As described below, the glass composition in this specification is expressed in terms of oxide-based mass percentage, but the changes in glass components before and after ion exchange are based on oxide-based mole percentage.

[0015] In this specification, the glass composition is expressed as a mass percentage based on oxides, and mass% may be simply referred to as %. Furthermore, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower and upper limits.

[0016] <Glass Plate> The glass according to this embodiment has a first main surface and a second main surface opposite to the first main surface, a thickness of 0.30 to 1.00 mm, and is characterized in that it satisfies the following formulas (1) and (2) in terms of mass percentage based on oxides: 0.03≦(ΔSnO ２ ) Ｔ ≦1.0 (1) 0.20≦(ΔSnO ２ ) Ｂ ≦1.5 (2) (ΔSnO ２ ) Ｔ : [SnO at the center of the plate thickness ２ concentration (%)] to [SnO ２ concentration (%)] minus the value (%) (ΔSnO ２ ) Ｂ : [SnO on the second main surface ２ concentration (%)] to [SnO at the center of the plate thickness ２ Concentration (%) minus the value (%)

[0017] The glass sheet according to the present embodiment is preferably a glass sheet (float glass) manufactured by a float process. A float glass sheet has a bottom surface that contacts molten metal during forming and a top surface opposite to the bottom surface. In the present embodiment, when the glass sheet is a float glass sheet, it is preferable that the first main surface is the top surface and the second main surface is the bottom surface.

[0018] (SnO ２ The glass plate according to the present embodiment has a SnO concentration at the center of the plate thickness. ２ Concentration (%)] to [SnO on the first principal surface ２ concentration (%) (ΔSnO ２ ) Ｔ is 0.03% or more and 1.0% or less. (ΔSnO ２ ) Ｔ However, by making the refractive index distribution in the glass surface layer of the first main surface 0.03% or more and 1.0% or less, it is possible to improve the extraction efficiency of light emitted from the center of the glass plate thickness through the first main surface to the outside.

[0019] From the viewpoint of further increasing the light extraction efficiency, (ΔSnO ２ ) Ｔ is preferably 0.05% or more, and thereafter in steps of 0.07% or more, 0.10% or more, 0.13% or more, 0.15% or more, 0.17% or more, 0.20% or more, 0.23% or more, 0.25% or more, 0.28% or more, and 0.30% or more. ２ ) Ｔ may be 0.40% or more, 0.45% or more, or 0.50% or more. ２ ) Ｔ is preferably 0.90% or less, and thereafter in steps of 0.85% or less, 0.80% or less, 0.75% or less, 0.70% or less, 0.65% or less, 0.60% or less, 0.55% or less, and 0.50% or less.

[0020] The glass plate according to this embodiment has a structure in which [SnO ２ concentration (%)] to [SnO at the center of the plate thickness ２concentration (%) (ΔSnO ２ ) Ｂ is 0.20% or more and 1.5% or less. (ΔSnO ２ ) Ｂ However, by setting the refractive index to be 0.20% or more and 1.5% or less, a refractive index distribution is imparted to the surface layer of the glass of the second main surface, and the refractive index is made closer to that of the glass on the surface of the light-emitting component, thereby increasing the efficiency of light capture coming from the second main surface toward the center of the plate thickness, and as a result, the efficiency of light extraction from the first main surface can be improved.

[0021] From the viewpoint of further increasing the light extraction efficiency, (ΔSnO ２ ) Ｂ is preferably 0.25% or more, and thereafter in steps of 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, and 0.50% or more. ２ ) Ｂ may be 0.60% or more, 0.65% or more, or 0.70% or more. In addition, from the viewpoint of reducing the amount of deformation when heat is applied, (ΔSnO ２ ) Ｂ is preferably 1.4% or less, more preferably 1.3% or less, even more preferably 1.2% or less, particularly preferably 1.1% or less, and most preferably 1.0% or less.

[0022] The glass plate according to this embodiment has a SnO ２ Concentration (%)] to [SnO on the first principal surface ２ It is preferable that the value obtained by subtracting the [concentration (%)] from the refractive index (%) is 0 to 0.9%. By setting this value to 0 to 0.9%, it is possible to impart a refractive index distribution to the first main surface, thereby further improving the extraction efficiency of light emitted from the center of the glass plate thickness through the first main surface to the outside.

[0023] From the viewpoint of further improving the light extraction efficiency, the glass plate according to this embodiment has a SnO ２ Concentration (%)] to [SnO on the first principal surface ２The value obtained by subtracting [SnO concentration (%)] from [SnO concentration (%) at a depth of 100 μm from the first main surface] is more preferably 0.05% or more, further preferably 0.1% or more, and particularly preferably 0.2% or more. ２ Concentration (%)] to [SnO on the first principal surface ２ From the viewpoint of ion exchange efficiency, the value obtained by subtracting [SnO concentration (%) at a depth of 100 μm from the first main surface] may be 0.3% or more, or may be 0.4% or more. ２ Concentration (%)] to [SnO on the first principal surface ２ The value obtained by subtracting [SnO concentration (%)] from [SnO ２ Concentration (%)] to [SnO on the first principal surface ２ The value obtained by subtracting [SnO concentration (%) on the first principal surface] may be 0.4% or less, 0.3% or less, or 0.2% or less. ２ concentration (%)] is the SnO concentration at a depth of 10 μm from the first main surface. ２ This refers to the average tin oxide concentration converted into tin oxide.

[0024] The glass plate according to this embodiment has a second main surface containing SnO ２ Concentration (%)] to [SnO at a depth of 100 μm from the second main surface ２ The glass plate according to this embodiment is preferably such that the value obtained by subtracting the [SnO concentration (%) on the second main surface] from the [SnO concentration (%) on the second main surface] is 0.15% or more, and thereafter the value is preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, and 0.40% or more in a stepwise manner. ２ Concentration (%)] to [SnO at a depth of 100 μm from the second main surface ２Preferably, the value obtained by subtracting [SnO concentration (%)] from [SnO concentration (%)] is 1.4% or less, and thereafter, it is preferably 1.3% or less, 1.2% or less, 1.0% or less, 0.9% or less, 0.8% or less, and 0.7% or less in a stepwise manner. By having this value within the above numerical range, the second main surface has a refractive index distribution, which further increases the efficiency of light capture entering from the second main surface toward the center of the plate thickness, and as a result, the efficiency of light extraction from the first main surface can be further improved. Here, [SnO concentration (%) on the second main surface] ２ concentration (%)] is the SnO concentration at a depth of 10 μm from the second main surface. ２ This refers to the average tin oxide concentration converted into tin oxide.

[0025] From the viewpoint of further improving the light extraction efficiency, the glass plate according to this embodiment has a [SnO ２ Concentration (%)] to [SnO at a depth of 100 μm from the second main surface ２ The value obtained by subtracting the [SnO concentration (%)] from the [SnO concentration (%) in the second principal surface] is preferably 0.15% or more, and thereafter, stepwise, preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, and 0.40% or more. In addition, the value may be 0.5% or more, 0.6% or more, 0.7% or more, or 0.8% or more. From the viewpoint of reducing the amount of deformation when heat is applied, ２ Concentration (%)] to [SnO at a depth of 100 μm from the second main surface ２ The value obtained by subtracting the [concentration (%)] is preferably 1.4% or less, and thereafter, it is preferable to set it in stages to 1.3% or less, 1.2% or less, 1.0% or less, 0.9% or less, 0.8% or less, and 0.7% or less.

[0026] SnO ２ The concentration can be evaluated by XRF (X-ray Fluorescence Spectrometer). Examples of analytical conditions for the XRF method are as follows. Quantitative analysis is performed using SnO2, which is valued as a standard sample. ２Measurement can be performed by the calibration curve method using glass containing the compound. An example of a measurement device is the ZSX100 manufactured by Rigaku Corporation. Output: Rh 50 kV-72 mA Filter: OUT Attenuator: 1 / 1 Slit: S4 Analyzing crystal: LiF (200) Detector: PC Peak angle (2θ / deg.): 126.790 Peak measurement time (seconds): 40 B.G.1 (2θ / deg.): 124.25 B.G.2 (2θ / deg.): 129.55 B.G.1 Measurement time (seconds): 10 B.G.2 Measurement time (seconds): 10 PHA: 100-300 The concentration of tin oxide can also be measured using an electron probe microphone analyzer (EPMA) and a wavelength dispersive X-ray detector (WDX) attached thereto. Specifically, based on the measurement results of WDX analysis using an EPMA (JXA8600, manufactured by JEOL Ltd.), Sn present in divalent and tetravalent forms is converted to tetravalent form.

[0027] SnO on glass plate ２ As will be described later, the concentration distribution is determined by factors such as the rising speed, the hydrogen concentration in the air, the temperature of the molten metal bath and dealkalization treatment during forming by the float method in the production of a glass sheet, and the glass composition (e.g., SnO ２ The amount of the hydroxybenzoate can be adjusted by adjusting the amount of the hydroxybenzoate.

[0028] As an embodiment, in FIG. 1, the horizontal axis represents the depth from the first main surface, and the vertical axis represents SnO ２ 1 shows an example of the relationship between the concentration of SnO at the center of the thickness and the thickness of the glass plate of the present embodiment. In FIG. 1, t represents the plate thickness, and t / 2 represents the center of the thickness. As shown in FIG. 1, in the region from the first main surface to a depth x1, the concentration of SnO at the center of the thickness decreases with increasing depth from the first main surface. ２ Gradually increase the concentration to SnO ２ In addition, in the region from the depth x2 to the second main surface, as the depth from the first main surface increases, the concentration of SnO gradually decreases from the concentration at the center of the plate thickness. ２ The concentration increases.

[0029] In the glass plate according to one embodiment, the depth x1 from the first main surface (denoted by a1 in FIG. 1 ) is preferably 1 / 10 or more and less than 1 / 2, more preferably 1 / 9 or more and 1 / 3 or less, even more preferably 1 / 8 or more and 1 / 4 or less, and particularly preferably 1 / 7 or more and 1 / 5 or less of the plate thickness t, from the viewpoint of further improving the light extraction efficiency.

[0030] In the glass plate according to one embodiment, the depth from x2 to the second main surface (indicated by a2 in FIG. 1 ) is preferably 1 / 10 or more and less than 1 / 2, more preferably 1 / 9 or more and 1 / 3 or less, even more preferably 1 / 8 or more and 1 / 4 or less, and particularly preferably 1 / 7 or more and 1 / 5 or less of the plate thickness t, from the viewpoint of further improving the light extraction efficiency.

[0031] In the glass plate according to one embodiment, the horizontal axis represents the depth (mm) from the first main surface, and the vertical axis represents the SnO ２ When the concentration is expressed as (wt %), from the viewpoint of further improving the light extraction efficiency, the gradient (wt % / mm) at the depth from the first main surface to x1 is preferably 0.01 or more and 5.0 or less, more preferably 0.1 or more and 3.0 or less, even more preferably 0.2 or more and 2.0 or less, and particularly preferably 0.3 or more and 1.5 or less.

[0032] In the glass plate according to one embodiment, the horizontal axis represents the depth (mm) from the first main surface, and the vertical axis represents the SnO ２ When the concentration is expressed as (wt %), from the viewpoint of further improving the light extraction efficiency, the gradient (wt % / mm) at the depth from x2 to the second main surface is preferably 0.01 or more and 5.0 or less, more preferably 0.1 or more and 3.0 or less, even more preferably 0.2 or more and 2.0 or less, and particularly preferably 0.3 or more and 1.5 or less.

[0033] 2(a) and 2(b) show the relationship between the depth from the first main surface of the glass plate according to one embodiment and the SnO ２ As shown in (a) of FIG. 2, the glass plate according to one embodiment has a relationship between the SnO ２ ) Ｔ ≦(ΔSnO ２ ) ＢAs shown in FIG. 2(b), the glass plate according to one embodiment has a thickness of (ΔSnO ２ ) Ｔ ≧(ΔSnO ２ ) Ｂ This is preferable because it allows a larger refractive index difference to be created and improves the extraction efficiency.

[0034] (Composition) Hereinafter, the composition of the glass sheet according to this embodiment will be described. The composition of the glass sheet will be described as a matrix composition. The matrix composition is equivalent to the composition at the center of the sheet thickness. In this specification, the glass composition is expressed in mass percentage based on oxides, and the notation "%" indicates mass%.

[0035] The glass plate according to this embodiment is made of SnO ２ Sn can be divalent or tetravalent, but in this specification, SnO ２ The concentration is expressed based on SnO ２ When the content of SnO is 0.10% or more, the refractive index can be imparted to the glass surface layers on the first and second principal surfaces, thereby improving the light extraction efficiency. ２ If the content is too high, devitrification and coloring are likely to occur. Therefore, from the viewpoint of suppressing devitrification and coloring, SnO ２ The content is not more than 2.5%.

[0036] From the viewpoint of further improving the light extraction efficiency, SnO ２ The content of SnO is preferably 0.15% or more, and more preferably 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, and 0.45% or more in the following stepwise order. ２ The content is preferably 2.5% or less, more preferably 2.2% or less, particularly preferably 2.0% or less, and most preferably 1.8% or less.

[0037] The glass plate according to this embodiment is made of SiO ２ 55 to 75%, Al ２ O ３ 7.0-30%, Li ２ It is preferable that the O content is 4.5 to 13.0%.

[0038] More preferred compositions of the glass plate according to this embodiment include, for example, SiO ２ 55 to 75%, Al ２ O ３ 7.0-30%, Li ２ O 0.01-13.0%, Na ２ O 0 to 18%, ZrO ２ 0.1 to 6.0%, Y ２ O ３ 1.0 to 9.0%, P ２ O ５ Examples of compositions include those containing 0 to 5.0% of

[0039] SiO ２ is a component that forms the network structure of glass. It is also a component that increases chemical durability and can be a component that forms precipitated crystals. ２ The content of SiO is preferably 55% or more, and thereafter, stepwise, 56% or more, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, and 62% or more are preferred. ２ The content of SiO may be 64% or more, 66% or more, or 67% or more. ２ The content is preferably 75% or less, and thereafter in stages, 73% or less, 72% or less, 71% or less, 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, 65% or less, 64% or less, 63% or less, 62% or less, 61% or less, and 60% or less is preferred.

[0040] Al ２ O ３ is a component that increases the surface compressive stress due to chemical strengthening. ２ O ３The content of Al is preferably 7.0% or more, and thereafter in steps of 8.0% or more, 8.5% or more, 9.0% or more, 9.5% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, 19.0% or more, 20.0% or more, 21.0% or more, 22.0% or more, 23.0% or more, 24.0% or more, and 25.0% or more are preferred. On the other hand, from the viewpoint of preventing the devitrification temperature of the glass from becoming too high, Al is ２ O ３ The content is preferably 30% or less, and thereafter, stepwise increases to 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, and 18% or less are preferred.

[0041] Li ２ O is a component that forms surface compressive stress by ion exchange, and can also be a component of precipitated crystals. ２ The O content is preferably 0.01% or more, and thereafter, in steps of 0.05% or more, 0.1% or more, 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, and 4.0% or more. ２ The content of O may be 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, or 6.5% or more. On the other hand, in order to stabilize the glass, Li ２ The O content is preferably 13.0% or less, and thereafter, stepwise, 12.0% or less, 11.0% or less, 10.5% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, and 5.0% or less are preferred.

[0042] Na ２ O is a component that improves the meltability of glass. ２ When O is contained, the content is preferably 0.2% or more, and thereafter, the content is preferably 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, and 1.0% or more in a stepwise manner. ２If there is too much O, crystals become difficult to precipitate or chemical strengthening properties deteriorate, so 18% or less is preferable, and thereafter, it is stepwise increased to 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, and 1.0% or less is preferable.

[0043] K ２ O is Na ２ Like O, K is a component that lowers the melting temperature of glass and may be contained. ２ When O is contained, the content thereof is preferably 0.1% or more, more preferably 0.2% or more, even more preferably 0.3% or more, particularly preferably 0.4% or more, and most preferably 0.5% or more. ２ If O is too much, the chemical strengthening properties or chemical durability will decrease, so 8.0% or less is preferable, and thereafter, in steps of 5.0% or less, 3.0% or less, 2.0% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, and 1.0% or less is preferable.

[0044] The glass plate according to this embodiment is made of Na ２ O and K ２ Total content of Na and O ２ O+K ２ The content of O is preferably 0% or more and 3.0% or less. From the viewpoint of improving the meltability of the glass, Na ２ O+K ２ O is more preferably 0.2% or more, even more preferably 0.4% or more, even more preferably 0.6% or more, particularly preferably 0.7% or more, and most preferably 0.8% or more. ２ O+K ２ If the O content is too high, the chemical strengthening properties or chemical durability will decrease, so the O content is more preferably 2.7% or less, even more preferably 2.5% or less, still more preferably 2.3% or less, particularly preferably 2.2% or less, and most preferably 2.1% or less.

[0045] The glass plate according to this embodiment is ２ O, Na ２ O and K ２ Total O content Li ２ O + Na ２ O+K２ O to R ２ As O, R ２ The content of O is preferably 4.5% or more and 16% or less. From the viewpoint of improving the meltability of the glass, R ２ O is more preferably 5.0% or more, further preferably 6.0% or more, particularly preferably 6.5% or more, and most preferably 7.0% or more. ２ O is preferably 15% or less, and thereafter, stepwise, preferably, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, and 7% or less.

[0046] The glass plate according to this embodiment is made of K ２ O / R ２ O is preferably 0.20 or less, more preferably 0.15 or less, even more preferably 0.13 or less, particularly preferably 0.12 or less, and most preferably 0.11 or less. ２ O / R ２ The lower limit of O is not particularly limited, but may be, for example, 0.003 or more, 0.01 or more, 0.03 or more, 0.05 or more, or 0.10 or more.

[0047] ZrO ２ is a component that can form crystal nuclei during crystallization treatment and may be contained. ２ The content of ZrO is preferably 0.1% or more, and thereafter, it is preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, and 2.5% or more in a stepwise manner. ２ On the other hand, in order to suppress devitrification during melting, the content of ZrO ２ The content is preferably 6.0% or less, and thereafter, stepwise, preferably 5.5% or less, 5.0% or less, 4.5% or less, 4.2% or less, 4.0% or less, 3.5% or less, and 3.0% or less.

[0048] Also, Li ２ O, Na ２ O and K ２ Total O content Li ２ O + Na２ O+K ２ O to R ２ O is ZrO ２ / R ２ From the viewpoint of increasing chemical durability, O is preferably 0.1 or more, and more preferably 0.2 or more. From the viewpoint of increasing transparency after crystallization, ZrO ２ / R ２ O is preferably 0.8 or less, more preferably 0.6 or less.

[0049] Y ２ O ３ is a component that makes it difficult for chemically strengthened glass to scatter fragments when broken, and may be contained. ２ O ３ The content of Y is preferably 1.0% or more, more preferably 1.3% or more, even more preferably 1.6% or more, particularly preferably 1.9% or more, and most preferably 2.1% or more. ２ O ３ The content is preferably 9.0% or less, more preferably 8.0% or less, even more preferably 7.0% or less, particularly preferably 6.0% or less, and most preferably 5.0% or less.

[0050] P ２ O ５ is not essential, but has the effect of promoting phase separation of glass and accelerating crystallization, and may be contained. ２ O ５ When P is contained, the content is preferably 0.2% or more, and thereafter, stepwise, 0.4% or more, 0.6% or more, 0.8% or more, 1.0% or more, 1.5% or more, 2.0% or more, and 2.5% or more are preferred. ２ O ５ If the content of P is too high, phase separation occurs easily when melted, and acid resistance is significantly reduced. ２ O ５ The content is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less, particularly preferably 3.7% or less, and most preferably 3.5% or less.

[0051] TiO ２is a component that can form crystal nuclei during crystallization treatment and may be contained. ２ is not essential, but when contained, it is preferably 0.01% or more, and thereafter, it is preferably 0.05% or more, 0.08% or more, 0.10% or more, 0.15% or more, and 0.20% or more in a stepwise manner. ２ The content of TiO may be 1.0% or more, or may be 1.5% or more. On the other hand, in order to suppress devitrification during melting and to impart color to the glass, TiO ２ The content of is preferably 3.0% or less, and thereafter, stepwise, preferably, 0.8% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, and 0.15% or less.

[0052] B ２ O ３ Although not essential, B is a component that improves the chipping resistance and meltability of the glass for chemical strengthening or the chemically strengthened glass, and may be contained. ２ O ３ When B is contained, the content is preferably 0% or more and 3.0% or less. ２ O ３ From the viewpoint of further improving the meltability, the content of B is more preferably 0.2% or more, even more preferably 0.4% or more, particularly preferably 0.6% or more, and most preferably 0.8% or more. On the other hand, in order to suppress the occurrence of striae during melting and to prevent the deterioration of the quality of the glass for chemical strengthening due to the easy phase separation, B ２ O ３ The content is more preferably 2.0% or less, further preferably 1.5% or less, particularly preferably 1.0% or less, and most preferably 0.8% or less.

[0053] BaO, SrO, MgO, CaO, and ZnO are components that improve the meltability of glass and may be contained. When these components are contained, the total content of BaO, SrO, MgO, CaO, and ZnO (BaO + SrO + MgO + CaO + ZnO) is preferably more than 0% and not more than 3.0%. From the viewpoint of further improving the meltability of glass, BaO + SrO + MgO + CaO + ZnO is more preferably 0.1% or more, even more preferably 0.2% or more, particularly preferably 0.3% or more, and most preferably 0.5% or more. On the other hand, from the viewpoint of suppressing a decrease in the ion exchange rate, BaO + SrO + MgO + CaO + ZnO is preferably 2.5% or less, and thereafter, stepwise, preferably 2.0% or less, 1.8% or less, 1.5% or less, 1.0% or less, 0.8% or less, 0.6% or less, 0.4% or less, and 0.2% or less.

[0054] Among the above components, BaO, SrO, and ZnO may be included to improve the refractive index of the residual glass, bringing it closer to the precipitated crystalline phase, thereby improving the light transmittance of the crystallized glass and reducing the haze value. In this case, the total content of BaO + SrO + ZnO is preferably 0% or more and 1.0% or less. BaO + SrO + ZnO is more preferably 0.05% or more, even more preferably 0.10% or more, particularly preferably 0.20% or more, and most preferably 0.30% or more. On the other hand, these components may reduce the ion exchange rate. From the viewpoint of improving chemical strengthening properties, BaO + SrO + ZnO is more preferably 0.8% or less, even more preferably 0.6% or less, and particularly preferably 0.5% or less. Furthermore, BaO + SrO + ZnO may be 0.4% or less.

[0055] CeO ２ has the effect of oxidizing the glass and may suppress coloring, and may be contained. ２ When CeO is contained, the content is preferably 0% or more and 1.0% or less. ２ The content of CeO is more preferably 0.1% or more, further preferably 0.2% or more, particularly preferably 0.3% or more, and most preferably 0.4% or more. ２ When used as an oxidizing agent, CeO ２In order to increase transparency, the content is more preferably 0.8% or less, further preferably 0.7% or less, particularly preferably 0.6% or less, and most preferably 0.5% or less.

[0056] When the glass is used in a colored state, a coloring component may be added to the glass in a range that does not impede the achievement of the desired chemical strengthening properties. ３ O ４ , MnO, MnO ２ , FeO, Fe ２ O ３ , NiO, CuO, Cu ２ O, Cr ２ O ３ , V ２ O ５ , Bi ２ O ３ , SeO ２ , Se, Er ２ O ３ , Nd ２ O ３ , Eu ２ O ３ , Pr ６ O １１ are preferred. The total content of the coloring components is preferably 1.0% or less, more preferably 0.8% or less, even more preferably 0.6% or less, and most preferably 0.4% or less. If a higher visible light transmittance of the glass is desired, it is preferable that these components are substantially not contained.

[0057] SO 4 is used as a fining agent when melting glass. ３ , chloride, fluoride, etc. may be contained as appropriate. ２ O ３ It is preferable that As is not contained. ２ O ３ When it is contained, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably not contained.

[0058] The composition of the glass is not particularly limited, but specific examples include the following glass compositions: (1) In terms of mass % based on oxides, SiO ２ 60 to 66%, Al ２ O ３18.0-23%, Li ２ O 4.5 to 9.0%, SnO ２ (2) Glass containing 1.50 to 2.5% of SiO ２ 60 to 66%, Al ２ O ３ 7.0-18%, Li ２ O 7 to 11.0%, SnO ２ (3) Glass containing 1.00 to 2.5% of SiO ２ 65 to 75%, Al ２ O ３ 8.0-13%, Li ２ O 7 to 11.0%, SnO ２ (4) Glass containing 1.50 to 2.5% of SiO ２ 65 to 75%, Al ２ O ３ 18.0-23%, Li ２ O 4.5 to 9.0%, SnO ２ (5) Glass containing 0.10 to 2.5% of SiO ２ 60 to 66%, Al ２ O ３ 12.0-18%, Li ２ O 4.5 to 9.0%, SnO ２ (6) Glass containing 0.50 to 1.5% of SiO ２ 60 to 66%, Al ２ O ３ 23-27%, Li ２ 3.5-5.0% O, Na ２ O 1.0 to 2.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2%, ZrO ２ 2.5 to 3.5%, SnO ２ (7) Glass containing 0.4 to 1.0% of SiO ２ 60 to 66%, Al ２ O ３ 18-24%, Li ２ 4.0-6.0% O, Na ２ O 0.5 to 1.5%, K ２0.1-1.5% O, TiO ２ 0.01 to 0.2%, ZrO ２ 2.0 to 3.5%, SnO ２ (8) Glass containing 1.5 to 3.0% of SiO ２ 56 to 60%, Al ２ O ３ 25-29%, Li ２ 4.5-7.0% O, Na ２ O 0.3 to 1.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2%, ZrO ２ 2.5 to 3.5%, SnO ２ (9) Glass containing 1.5 to 3.0% of SiO ２ 60 to 64%, Al ２ O ３ 20-24%, Li ２ 3.5-5.5% O, Na ２ O 0.8 to 1.5%, K ２ 0.5-1.0% O, TiO ２ 0.01 to 0.2%, ZrO ２ 2.5 to 3.5%, SnO ２ (10) Glass containing 1.5 to 3.0% of SiO ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2%, ZrO ２ (11) Glass containing 2.0 to 3.0% of SiO ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2%, ZrO ２ 2.0 to 3.5%, SnO２ Glass containing 1.5 to 3.0%

[0059] (Visible light transmittance) The glass plate according to this embodiment preferably has a visible light transmittance of 91.0% or more when converted to a thickness of 0.7 mm, so that when used as a protective member for a display device, the display screen is easy to see. The visible light transmittance is more preferably 91.2% or more, and even more preferably 91.4% or more. The higher the visible light transmittance, the more preferable it is, but it is usually 92% or less. Note that the visible light transmittance of ordinary amorphous glass is about 90%. The visible light transmittance can be measured by a method in accordance with JIS R3106 (2019).

[0060] (Haze Value) The haze value of the glass plate according to this embodiment, when measured at a thickness of 0.7 mm, is preferably 0.50% or less, more preferably 0.30% or less, even more preferably 0.20% or less, particularly preferably 0.10% or less, and most preferably 0.05% or less. The smaller the haze value, the better. The haze value is a value measured according to JIS K7136 (2000).

[0061] In addition, when the total visible light transmittance of a crystallized glass having a thickness of t [mm] is T [%] and the surface reflectance of one side is R [%], by invoking the Lambert-Beer law and using the constant α, T / 100 = (1 - R / 100) ２ × exp(-αt). If α is expressed as R, T, and t, and t = 0.7 mm, R does not change depending on the plate thickness, so the total light visible light transmittance T ０．７ / 100 is T ０．７ / 100=T / 100 ０．７／ｔ / (1-R / 100)^(1.4 / t-2) where X^Y is X Ｙ Represents.

[0062] (Thickness) The thickness of the glass plate according to this embodiment is 0.30 to 1.00 mm. The thickness is preferably 0.90 mm or less, more preferably 0.80 mm or less, even more preferably 0.70 mm or less, particularly preferably 0.65 mm or less, and most preferably 0.60 mm or less. From the viewpoint of further increasing the strength, the thickness is preferably 0.35 mm or more, more preferably 0.40 mm or more, even more preferably 0.45 mm or more, and particularly preferably 0.50 mm or more.

[0063] The shape of the glass plate according to this embodiment may be a shape other than a plate shape depending on the product to which it is applied, its intended use, etc. Furthermore, the glass plate may have a rim shape with a different peripheral thickness, etc. Furthermore, the shape of the glass plate is not limited thereto; for example, the two main surfaces may not be parallel to each other, and one or both of the two main surfaces may be entirely or partially curved. More specifically, the glass plate may be, for example, a flat glass plate without warping, or a curved glass plate having a curved surface.

[0064] <<Crystalized Glass>> The glass plate according to this embodiment is preferably crystallized glass. Crystallized glass is obtained by heat-treating amorphous glass to crystallize it. The glass composition of the crystallized glass is the same as the composition of the amorphous glass before crystallization. That is, the matrix composition of the crystallized glass according to this embodiment is the same as the composition of the glass plate according to the above-mentioned embodiment, and the preferred composition range is also the same.

[0065] As used herein, "glass-ceramics" refers to glass in which diffraction peaks indicating crystallization are observed by X-ray diffraction (XRD). X-ray diffraction measurement can be performed, for example, using CuKα radiation to measure 2θ in the range of 10° to 80°. Examples of crystals that contain lithium include β-spodumene crystals, lithium disilicate crystals, β-quartz crystals, lithium metasilicate crystals, and lithium phosphate crystals. These crystals may form solid solutions and dissolve various elements. In particular, the elements that dissolve are alkali metals (Na, K) and alkaline earth metals (Mg, Ca, Sr, Ba), but this is not a limitation. Furthermore, crystals that do not contain lithium include ZrO ２ and crystals of solid solutions thereof. Examples of elements that form a solid solution include, but are not limited to, Y and Sn. The crystallized glass preferably contains β-spodumene as crystals. Since β-spodumene has a denser crystal structure than β-quartz solid solution, it is believed that when ions in the precipitated crystals are replaced with larger ions by ion exchange treatment for chemical strengthening, high compressive stress is generated, thereby enhancing the effect of chemical strengthening. The crystallized glass may also contain virgilite. Virgilite is also called keatite, and like β-spodumene, it contains LiAlSi ２ O ６ However, the crystal structure is different.

[0066] The crystallization rate of crystallized glass is preferably 60% or more, more preferably 65% ​​or more, more preferably 70% or more, particularly preferably 75% or more, in order to increase mechanical strength.In addition, in order to increase transparency, it is preferably 90% or less, more preferably 85% or less, particularly preferably 80% or less.The low crystallization rate is also excellent in that it is easy to be heated and bent and molded.

[0067] The crystallinity can be calculated from the X-ray diffraction intensity by the Rietveld method, which is described in "Crystal Analysis Handbook" edited by the Editorial Committee of the Crystallographic Society of Japan (Kyoritsu Shuppan, 1999, pp. 492-499).

[0068] In order to improve transparency, the average particle size of the precipitated crystals of the crystallized glass is preferably 150 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and particularly preferably 20 nm or less. The average particle size of the precipitated crystals can be determined from a transmission electron microscope (TEM) image. It can also be estimated from a scanning electron microscope (SEM) image.

[0069] <<Chemically strengthened glass>> The glass plate according to this embodiment is preferably chemically strengthened glass. The chemically strengthened glass according to this embodiment is obtained by chemically strengthening the glass plate according to the above-described embodiment. That is, the matrix composition of the chemically strengthened glass according to this embodiment is the same as the composition of the glass plate according to the above-described embodiment, and the preferred composition range is also the same.

[0070] When chemically strengthened glass is plate-shaped, the content ratio of alkali metal elements differs between the surface and the center in the thickness direction. On the other hand, except in cases where extreme ion exchange treatment has been performed, the glass composition at the deepest part from the surface of the chemically strengthened glass is the same as the base composition of the chemically strengthened glass. When chemically strengthened glass is plate-shaped, the deepest part from the glass surface is, for example, a depth of 1 / 2 of the plate thickness t.

[0071] (Stress characteristics) In this specification, the "depth of compressive stress layer (DOL)" is the depth at which the compressive stress value CS becomes zero. ０ The compressive stress layer depth DOL can be measured using a surface stress meter [for example, a surface stress meter (FSM-6000) manufactured by Orihara Seisakusho]. The preferred thickness (t) and preferred shape of the chemically strengthened glass according to this embodiment are the same as the preferred thickness (t) and shape of the glass plate according to this embodiment described above.

[0072] The chemically strengthened glass according to this embodiment has a surface compressive stress value CS ０ is preferably 300 MPa or more, more preferably 350 MPa or more, even more preferably 400 MPa or more, and even more preferably 450 MPa or more. ０ The upper limit of the surface compressive stress value CS ０ may be, for example, 1400 MPa or less.

[0073] If the compressive stress layer depth DOL of the chemically strengthened glass according to this embodiment is too large relative to the thickness t (mm), the CT may become too large, so it is preferably 0.30t or less, more preferably 0.20t or less. Moreover, from the viewpoint of improving strength, the DOL is preferably 0.10t or more, more preferably 0.15t or more.

[0074] (Reflectivity) The chemically strengthened glass according to this embodiment preferably has a reflectivity of 4.4% or less on the first main surface. Having a reflectivity of 4.4% or less on the first main surface can improve the extraction efficiency of light emitted from the center of the glass thickness through the first main surface to the outside. The reflectivity on the first main surface is more preferably 4.3% or less, even more preferably 4.2% or less, and particularly preferably 4.1% or less.

[0075] The chemically strengthened glass according to this embodiment preferably has a reflectance of 4.4% or more at the second main surface. Having a reflectance of 4.4% or more at the second main surface increases the efficiency of light entering from the second main surface toward the center of the plate thickness, thereby resulting in an improved light extraction efficiency from the first main surface. The reflectance at the second main surface is more preferably 4.45% or more, even more preferably 4.50% or more, and particularly preferably 4.55% or more.

[0076] Reflectance can be measured using a UV-Vis spectrophotometer by installing a reflectance unit (e.g., a Perkin Elma Lambda 900 and an automatic angle-variable universal reflectance accessory). To measure only one surface, it is necessary to eliminate reflection from the surface opposite the measurement surface. This can be done, for example, by roughening the surface with a file or by installing a prism to allow light to escape.

[0077] <Application>

[0078] The glass plate according to this embodiment can be used as a cover glass for mobile electronic devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet terminals. It is also useful as a cover glass for electronic devices that are not intended to be portable, such as televisions (TVs), personal computers (PCs), and touch panels. It is also useful as a building material such as window glass, a tabletop, the interior of automobiles and airplanes, and the like, and as a cover glass therefor (for example, an in-vehicle cover glass).

[0079] The glass plate according to this embodiment can be bent or formed into a shape other than a flat plate before or after chemical strengthening, and is therefore useful for applications such as housings having curved surfaces.

[0080] <<Method for Manufacturing Glass Plate>> The method for manufacturing a glass plate according to this embodiment preferably includes at least the following step (1), more preferably includes at least one of the following steps (2) and (3) in addition to step (1), and further preferably includes the following steps (1) to (3): (1) Step of producing amorphous glass, (2) Step of heat-treating glass to obtain crystallized glass, and (3) Step of ion-exchange-treating glass to obtain chemically strengthened glass. Each step will be described below.

[0081] (1) Step of Producing Amorphous Glass Amorphous glass can be produced, for example, by the following method. Glass raw materials are blended to obtain glass of a desired composition, and the mixture is heated and melted in a glass melting furnace. The molten glass is then homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate of a predetermined thickness by a known forming method, followed by annealing.

[0082] The forming method is preferably a float method. The float method refers to a method in which molten glass is poured onto a molten metal bath and formed into a sheet. In this specification, the upstream side of the molten metal bath refers to the side into which the molten glass flows, and the downstream side refers to the side from which the glass formed into a ribbon shape is discharged.

[0083] Fig. 3 shows a schematic diagram of a glass manufacturing apparatus using the float process. As shown in Fig. 3, the glass manufacturing apparatus using the float process includes a melting furnace 10, a float bath 20, and an annealing furnace (lehr) 30. In manufacturing glass using the float process, glass raw materials are first melted in the melting furnace 10 to obtain molten glass. The melting furnace 10 includes a melting furnace 11, in which glass raw materials 1 charged therein are melted to obtain molten glass 2. More specifically, the melting furnace 11 includes a melting tank 12 on the upstream side and a cooling tank 13 on the downstream side, which are connected by a neck 14 (or throat). The glass raw materials 1 are melted on the upstream side (i.e., the melting tank) to obtain molten glass 2, and the temperature of the molten glass 2 is adjusted on the downstream side.

[0084] Next, molten glass 2 is continuously supplied from the upstream side onto the surface of the molten metal bath 21 stored in the float bath 20 to form a glass ribbon 3. The formed glass ribbon 3 is then drawn out from the downstream end of the float bath 20 and introduced into an annealing furnace (lehr) 30 where it is annealed to produce sheet glass. The glass ribbon 3 introduced into the lehr 30 is annealed while being transported to the annealing furnace (not shown) by a transport means such as a roller conveyor. Because the molten glass 2 on the molten metal bath 21 and the glass ribbon 3 in the lehr 30 are continuous, the transport speed (lehr speed) within the lehr 30 depends on the speed at which the molten glass 2 flows from upstream to downstream on the molten metal bath 21. Because the glass ribbon 3 in the lehr 30 is solidified but the molten glass 2 flows, the speed of the molten glass 2 is slower than the lehr speed, and the speed of the molten glass 2 on the molten metal bath 21 tends to be faster downstream. The type of molten metal is not particularly limited, but examples include molten tin.

[0085] As described above, in this embodiment, the SnO ２ The concentration distribution is determined by the following factors during forming by the float method: 1) the layer speed, 2) the hydrogen concentration in the air, 3) the temperature of the molten metal bath, and 4) the glass composition (e.g., SnO ２ The amount can be adjusted by adjusting the content of the hydroxybenzoates, etc. Each item is explained below.

[0086] 1) Rare speed during float forming The rare speed is preferably 20 m / h or more, more preferably 100 m / h or more, even more preferably 200 m / h or more, particularly preferably 300 m / h or more, and most preferably 400 m / h or more. If the rare speed is too high, the quality of the glass tends to deteriorate, so the rare speed is preferably 1200 m / h or less, more preferably 1000 m / h or less, even more preferably 900 m / h or less, particularly preferably 850 m / h or less, and most preferably 800 m / h or less.

[0087] 2) Hydrogen Concentration in the Atmosphere During Float Forming The hydrogen concentration in the atmosphere during float forming can be adjusted by the concentration of a gas such as a reducing gas or an oxidizing gas supplied to the glass during float forming, the amount of gas sprayed, the main surface to be sprayed, the treatment temperature and time, etc. Examples of the gas supply include supply from a hole in the ceiling that is spaced apart from the molten metal bath 21, and spraying the gas onto the glass sheet in an annealing furnace.

[0088] Examples of reducing gases include nitrogen gas, hydrogen gas, carbon monoxide gas, and a mixture thereof. The reducing gas may contain an inert gas such as air, nitrogen, or argon as a carrier gas. The reducing gas can be supplied, for example, from a hole in the ceiling spaced apart from the molten metal bath 21. Specific examples of reducing gas treatment conditions include a mixed gas flow rate of 0.1 to 100 cc / min and a treatment temperature of 600 to 1200°C. The mixed gas is, for example, a mixed gas of nitrogen gas and hydrogen gas, containing 80 to 99.5% by volume of nitrogen gas and 0.5 to 20% by volume of hydrogen gas.

[0089] The oxidizing gas may be, for example, sulfur dioxide (SO ２Examples of suitable oxidizing gases include fluorine-containing gas, hydrofluoric acid gas, oxygen gas, or a mixture thereof. The oxidizing gas may contain an inert gas such as air, nitrogen, or argon as a carrier gas. The oxidizing gas may further contain water vapor. The oxidizing gas is sprayed onto the main surfaces (preferably at least the top surface, specifically, for example, only the first main surface or both the first and second main surfaces) of the glass sheet in an annealing furnace. Specific examples of oxidizing gas treatment conditions include a mixed gas flow rate of 0.1 to 100 cc / min and a treatment temperature of 600 to 1200°C. The mixed gas may have an oxygen content ranging from 0.5% by volume to 10% by volume or higher. In some embodiments, the mixed gas may be oxygen gas with a maximum concentration of 100% by volume.

[0090] 3) Temperature of the molten metal bath during float forming The temperature of the molten metal bath is preferably 700° C. or higher, more preferably 800° C. or higher, even more preferably 850° C. or higher, and particularly preferably 900° C. or higher. From the viewpoint of volatilization of metallic tin, the temperature is preferably 1300° C. or lower, more preferably 1250° C. or lower, even more preferably 1200° C. or lower, and particularly preferably 1150° C. or lower.

[0091] 4) Glass composition SnO in glass plate ２ The concentration distribution is the same as the base composition of SnO ２ It can also be adjusted by adjusting the concentration. ２ The preferred range of the concentration is the same as that described above in the section <Glass Plate> (Composition).

[0092] (2) Process of Heat-treating Glass to Obtain Crystallized Glass Crystallized glass can be obtained by heat-treating the amorphous glass obtained by the above procedure (heat treatment). In this case, the heat treatment includes a multi-stage heat treatment of two or more stages. A multi-stage heat treatment refers to a heat treatment in which a predetermined temperature range is maintained for a predetermined time, and the temperature range is changed multiple times. A specific example of a multi-stage heat treatment is a two-stage heat treatment in which the temperature is raised from room temperature to a first treatment temperature and maintained for a certain time, and then maintained at a second treatment temperature higher than the first treatment temperature for a certain time.

[0093] In the case of two-stage heat treatment, the first treatment temperature is preferably in a temperature range where the crystal nucleation rate is high in the glass composition, and the second treatment temperature is preferably in a temperature range where the crystal growth rate is high in the glass composition. Also, it is preferable to maintain the first treatment temperature for a long time so that a sufficient number of crystal nuclei are generated. By generating a large number of crystal nuclei, the size of each crystal becomes small, and highly transparent crystallized glass can be obtained.

[0094] In the case of the two-stage heat treatment, the first treatment temperature is, for example, 550°C to 800°C, and the second treatment temperature is, for example, 850°C to 1000°C. After being held at the first treatment temperature for 2 hours to 10 hours, the second treatment temperature is held for 2 hours to 10 hours.

[0095] The temperature increase and decrease rates in the heat treatment at each stage are preferably 5 to 120°C / min. A temperature increase and decrease rate of 5°C / min or more is preferable because it can follow the crystal growth rate within the material. On the other hand, a temperature increase and decrease rate of 120°C / min or less is preferable because it can suppress deformation of the material.

[0096] The molten glass may be homogenized and formed into a glass plate of a predetermined thickness, or the molten glass may be formed into a block, followed by continuous crystallization. The crystallized glass obtained by the above procedure may be ground and polished as necessary to form a crystallized glass plate.

[0097] (3) Step of subjecting glass to ion exchange treatment to obtain chemically strengthened glass In this embodiment, the chemical strengthening treatment (ion exchange treatment) is performed by immersing the glass plate for 0.1 to 500 hours in a molten salt such as potassium nitrate heated to 360 to 600° C. The heating temperature of the molten salt is preferably 375 to 500° C., and the immersion time of the glass plate in the molten salt is preferably 0.3 to 200 hours.

[0098] Examples of molten salts used in chemical strengthening include nitrates, sulfates, carbonates, and chlorides. Nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These molten salts may be used alone or in combination.

[0099] In this embodiment, the treatment conditions for the chemical strengthening treatment are determined based on the characteristics and composition of the chemically strengthened glass, the type of molten salt, and the chemical strengthening characteristics such as the surface compressive stress and the depth of the compressive stress layer desired for the final chemically strengthened glass. Appropriate conditions may be selected.

[0100] In particular, it is preferable to chemically strengthen amorphous glass or crystallized glass, which has a high fracture toughness value, for a long time. When the ion exchange reaction progresses due to the chemical strengthening treatment for a long time, a large compressive stress is generated in the surface layer, and at the same time, a compressive stress is reduced mainly near the surface due to structural relaxation, making it easier to achieve the compressive stress balance of this embodiment.

[0101] In addition, in this embodiment, the chemical strengthening treatment may be performed only once, or may be performed a plurality of times under two or more different conditions (multi-stage strengthening).

[0102] <Laminate> The laminate according to this embodiment is a laminate including the glass plate according to the embodiment described above and a liquid crystal glass plate, wherein a first main surface of the glass plate is the outermost surface of the laminate, a second main surface of the glass plate is a lamination surface with the liquid crystal glass plate, and the absolute value of the difference between the refractive index of the second main surface of the glass plate measured with a prism coupler and the refractive index of the liquid crystal glass plate measured with a prism coupler is 0.001 to 0.20.

[0103] In the laminate according to this embodiment, the absolute value of the difference between the refractive index of the second main surface of the glass plate measured with a prism coupler and the refractive index of the liquid crystal glass plate measured with a prism coupler is preferably 0.001 to 0.20, which makes it easier for light to enter the glass plate from the liquid crystal glass plate and reduces light loss.

[0104] In the laminate according to this embodiment, from the viewpoint of further suppressing the loss of light entering the glass plate from the liquid crystal glass plate, the absolute value of the difference between the refractive index measured with a prism coupler of the second main surface of the glass plate and the refractive index measured with a prism coupler of the liquid crystal glass plate is more preferably 0.10 or less, even more preferably 0.050 or less, still more preferably 0.030 or less, and particularly preferably 0.010 or less.

[0105] In the laminate according to this embodiment, the second main surface of the glass plate is the lamination surface with the liquid crystal glass plate, but an intermediate layer may be included between the glass plate and the liquid crystal glass plate. Examples of the intermediate layer include an adhesive layer, a printed layer, and a functional layer (e.g., an optical filter layer, a refractive index matching layer). In the laminate according to this embodiment, a functional layer (e.g., an antifouling layer, an antireflection layer) may be laminated on the first main surface of the glass plate.

[0106] <Display Device> The display device according to this embodiment includes the glass plate according to the embodiment described above or the laminate according to the embodiment described above. Examples of the display device according to this embodiment include display devices such as in-vehicle car navigation systems and portable display devices such as smartphones.

[0107] The present invention will be described in more detail below using examples, but the present invention is not limited to these. Examples 1 to 20 are working examples, and Examples 21 to 31 are comparative examples.

[0108] <Examples 1 to 20: Production of Glass> Glasses were produced by the float process so as to have the compositions shown in mass percentages based on oxides in Tables 1 to 3. For Examples 4, 6 to 8, 10, 12, and 14, two-stage heat treatment was carried out under the conditions shown in the tables to obtain glass plates of crystallized glass.

[0109] <Examples 21 to 31: Glass Production> Glass raw materials were mixed to obtain the compositions shown in Tables 3 and 4, expressed in mass percentages based on oxides, and weighed to give 400 g of glass. The mixed raw materials were then placed in a platinum crucible and placed in an electric furnace at 1500 to 1700 °C, melted for approximately 3 hours, degassed, and homogenized. The resulting molten glass was poured into a metal mold and held at a temperature approximately 50 °C higher than the glass transition point for 1 hour, then cooled to room temperature at a rate of 0.5 °C / min to obtain a glass block. The resulting glass block was cut and ground, and finally both sides were polished to obtain a glass plate with a thickness of 0.7 mm. For Examples 25, 27, and 28, a two-stage heat treatment was performed under the conditions shown in Table 4 to obtain a crystallized glass plate.

[0110] <Glass Evaluation> The glass plates obtained above were evaluated as follows. For each glass, the tin oxide concentration (SnO ２ ) Ｔ and the tin oxide concentration (SnO ２ ) Ｂ The concentration of tin oxide was measured for the same glass plate as used in the Examples and Comparative Examples using an electron probe microanalyzer (EPMA) and a wavelength dispersive X-ray detector (WDX) attached thereto. Specifically, WDX analysis was performed using an EPMA (JXA8600, manufactured by JEOL Ltd.). From the measurement results, Sn present in divalent and tetravalent forms was converted to tetravalent form. Then, SnO was measured at a depth of 10 μm from the top surface. ２ The tin oxide concentration in terms of SnO on the top surface (first main surface) was averaged. ２ Concentration (SnO ２ ) Ｔ In addition, SnO ２ The converted tin oxide concentration was averaged and used as the SnO ２ Concentration (SnO ２ ) Ｂ In addition, the SnO ２ The converted tin oxide concentration was also measured in the same manner, and Δ(SnO ２ )Ｔ and Δ(SnO ２ ) Ｂ asked for.

[0111] Next, the refractive index of each glass was measured using a prism coupler (633 nm) on the top surface (first main surface) and bottom surface (second main surface). The results are shown in Tables 1 to 4. The "-" in the "crystallization conditions" column indicates that no crystallization treatment was performed.

[0112]

[0113]

[0114]

[0115]

[0116] As a result, in Examples 1 to 20, the refractive index of the bottom surface (second major surface) was greater than that of the top surface (first major surface). This suggests that when used as a cover glass for a display, the refractive index of the bottom surface can be made closer to the refractive index of the glass on the surface of the light-emitting component, making it easier for light to enter the second major surface from the liquid crystal glass plate. Furthermore, because the glass surface layer on the top surface has a refractive index distribution, it is expected that light will be more easily emitted from the center of the glass plate thickness through the first major surface to the outside. In other words, when used as a cover glass with the bottom surface of the glass plate facing the display, it is expected that the light extraction efficiency can be further improved.

[0117] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on December 6, 2023 (Patent Application No. 2023-206284), September 20, 2024 (Patent Application No. 2024-163789), July 17, 2024 (Patent Application No. 2024-114047), and July 17, 2024 (Patent Application No. 2024-114101), all of which are incorporated by reference in their entireties. Furthermore, all references cited herein are incorporated by reference in their entireties.

[0118] 1 glass raw material; 2 molten glass; 3 glass ribbon; 10 melting furnace; 11 melting furnace; 12 melting tank; 13 cooling tank; 14 neck; 20 float bath; 21 molten metal bath; 22 top roll; 23 restrictor; 30 annealing furnace (lehr)

Claims

1. A glass plate having a first main surface and a second main surface opposite to the first main surface, a thickness of 0.30 to 1.00 mm, and satisfying the following formulas (1) and (2) in terms of mass percentage based on oxides: 0.03≦(ΔSnO ２ ) Ｔ ≦1.0 (1) 0.20≦(ΔSnO ２ ) Ｂ ≦1.5 (2) (ΔSnO ２ ) Ｔ : [SnO at the center of plate thickness ２ Concentration (%) of SnO ２ Concentration (%)] subtracted from (ΔSnO ２ ) Ｂ : [SnO on the second main surface ２ Concentration (%) at the center of the plate thickness ２ Concentration (%) minus the value (%) 2. SnO at a depth of 100 μm from the first main surface, expressed as a mass percentage based on oxide ２ From the concentration (%), SnO ２ 2. The glass plate according to claim 1, wherein the concentration (%) is reduced by 0 to 0.9%.

3. SnO on the second main surface, expressed as a mass percentage based on oxide ２ From the concentration (%), SnO ２ 2. The glass plate according to claim 1, wherein the concentration (%) is reduced by 0.15 to 1.4%.

4. The parent composition is expressed as a mass percentage based on oxides: SiO ２ 55 to 75% Al ２ O ３ 7.0-30%, Li ２ The glass plate according to claim 1, containing 0.01 to 13.0% of O.

5. The parent composition is expressed as a mass percentage based on oxides, and is SiO ２ 55 to 75% Al ２ O ３ 7.0-30%, Li ２ O 0.01-13.0%, Na ２ O 0 to 18%, ZrO ２ 0.1 to 6.0%, Y ２ O ３ 1.0 to 9.0%, P ２ O ５ The glass plate according to claim 4, containing 0 to 5.0%.

6. The parent composition is expressed as a mass percentage based on oxides, and is SiO ２ 60 to 66% Al ２ O ３ 23-27%, Li ２ 3.5-5.0% O, Na ２ O 1.0 to 2.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5% SnO ２ The glass plate according to claim 4, containing 0.4 to 1.0% of 7. The parent composition is expressed as a mass percentage based on oxides: SiO ２ 60 to 66% Al ２ O ３ 18-24%, Li ２ 4.0-6.0% O, Na ２ O 0.5 to 1.5%, K ２ 0.1-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.0 to 3.5% SnO ２ The glass plate according to claim 4, containing 1.5 to 3.0% of 8. The parent composition is expressed as a mass percentage based on oxides: SiO ２ 56 to 60% Al ２ O ３ 25-29%, Li ２ 4.5-7.0% O, Na ２ O 0.3 to 1.0%, K ２ 0.1-0.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5% SnO ２ The glass plate according to claim 4, containing 1.5 to 3.0% of 9. The parent composition is expressed as a mass percentage based on oxides: SiO ２ 60 to 64%, Al ２ O ３ 20-24%, Li ２ 3.5-5.5% O, Na ２ O 0.8-1.5%, K ２ 0.5-1.0% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.5 to 3.5% SnO ２ The glass plate according to claim 4, containing 1.5 to 3.0% of 10. The parent composition is expressed as a mass percentage based on oxides, and is SiO ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ The glass plate according to claim 4, containing 2.0 to 3.0% of 11. The parent composition is expressed as a mass percentage based on oxides: SiO ２ 58 to 62%, Al ２ O ３ 21-25%, Li ２ 3.5-5.5% O, Na ２ O 0.5 to 1.5%, K ２ 0.3-1.5% O, TiO ２ 0.01 to 0.2% ZrO ２ 2.0 to 3.5% SnO ２ The glass plate according to claim 4, containing 1.5 to 3.0% of 12. The glass plate of claim 1, which is glass-ceramic.

13. The glass sheet according to claim 1, which is a chemically strengthened glass.

14. The glass sheet of claim 1 which is float glass.

15. The glass plate according to claim 1, which has a visible light transmittance of 91.0% or more when converted into a glass plate with a thickness of 0.7 mm.

16. A laminate comprising the glass plate according to claim 1 and a liquid crystal glass plate, wherein the surface of the glass plate that is laminated with the liquid crystal glass plate is the second main surface, and the absolute value of the difference between the refractive index of the second main surface of the glass plate measured with a prism coupler and the refractive index of the liquid crystal glass plate measured with a prism coupler is 0.001 to 0.

20.

17. A display device comprising a glass plate according to any one of claims 1 to 15 or a laminate according to claim 16.

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